Piano action



Aug. 3, 1965 w. H. BENDALL PIANO ACTION Filed July 12 INVENTOR.

United States Patent 3,198,653 PHANQB AQTEUN Wiifrid H. Bendali, Rfl. Box 3426, Stonington, Conn. Fiied l uiy 12, N63, Ser. No. 294,729 11 (or. 84 -243) This invention pertains to piano actions and related apparatus for instruments requiring playing key, percussion hammer and tone control means for the performance of music.

Despite numerous proposals for improved piano actions disclosed in the prior art current manufacture continues to produce action mechanisms essentially unchanged in design from those originated well over one hundred years ago. Since it is tacitly acknowledged in the industry that such actions are expensive to manufacture, regulate and maintain it may be assumed that the later proposals have not presented enough technical or economic advantages to justify acceptance.

It is an object of the present invention to provide an improved piano action of exceptional simplicity and manu facturing economy and embodying the mechanical design characteristics considered desirable for the accomplished keyboard technique.

A further object is to provide a piano action obviating the need for costly manufacturing procedures by drastically reducing the required number of parts and making them largely self-regulating in assembly and use.

A further object is to provide a piano action in which the relative weight and playing resistance of the co-operating parts can be readily modified to suit individual requirements.

A further object is to provide such piano apparatus conveniently adaptable for use in either horizontal or vertical instruments by simple modification of the playing key structure.

Another object is to provide a piano action with simpler and more efiicient tonal expression control means than available heretofore.

These objects and the structural details required to realize them are set forth in the following description and references to the drawings in which FIG. 1 is a side elevational view showing a horizontally disposed action assembly in the normal unoperated position.

FIG. 2 is a similar view showing the action assembly with the playing key depressed and the hammer rebounded from the string and held for repetition.

FIG. 3 is a larger scale cross-sectional view on the line 33 of FIG. 2 illustrating a detail of the hammer head construction.

In FIGS. 1 and 2 reference numeral iii designates a base line which may comprise the upper surface of a key bed integral with a piano case and having a key front downstop pad 11 thereon. A supporting bracket 20, mounted on the base, is provided with a pivotally adjustable rail 21, conveniently of structural angle form, having pivot means 22 secured to an end thereof. Rail adjustment means comprising a stub shaft 23 slotted for attachment to a leg of the rail angle extending normal to the playing key 3t) is provided with a screw-threaded extension 24 projecting through an arcuate slot 25 in the supporting bracket and secured with locknut 26. The other leg of the rail angle coplanar with the surface of the playing key has a portion of a length of flat spring material 27 attached thereto and a further portion 270 attached to the front part of the playing key. Secured thus the flat spring material is free to flex at a point between its areas of attachment substantially coaxial with rail pivot means 22. This arrangement ensures noiseless and frictionless pivotal action of the key with the important added advantage of key lateral alignment conveyed by the high stiffness of the spring material in the flat plane thereof.

The rear key portion 31 is angled upwardly as shown in the drawings and provided with a hammer rest pad 32 and, at its extreme rear end, with a segmental spherical recess 33 having a disk of resilient material 34 freely inserted therein and projecting segmentally therefrom to effect tangential actuating contact with the shank of the hammer 46*. Such contact results in incremental rotation of the disk with each actuation making the disk selfadjusting in use and ensuring uniformly distributed wear around its periphery. It is pertinent to observe here that in ordinary piano actions the complex interaction from key to hammer of a multiplicity of parts, each With its points of localized friction and wear, renders such actions inherently subject to maladjustment. In the present invention the complete elimination of such parts and the novel interpostion of a self-adjusting element at the one essential interaction point between key and hammer virtually eliminates such difficulties.

Since an identical working principle governs the use of the self-adjusting disk element 34 between key and hammer and of a similar disk element 41 between hammer and string in this action, the immediately following remarks on the structural and operating features of the element pertain to both uses.

As conveniently fabricated the disk may be die-cut from sheet material of the required resilience and density and will have a square-edged periphery with a diameter closely equal to the internal diameter of the spherical recess it is required to engage. Since the resilience of the disk enables it to be freely inserted therein the slightly smaller diameter of the edges of the recess provide the required light lateral restraint of the disk without restricting its freedom to rotate in response to tangential frictional impact with an actuated part. The incremental rotating force thus induced will be apparent when it is observed, in the case of the key and hammer shank disk contact, that the points of initial contact rotate in opposed arcs of different radius. Similarly the hammer head and string contact utilizes the directional difference of the arc of the hammer disk contact point with the substantially vertical motion of the string at the point of impact to impart a corresponding rotational component to the periphery of the hammer disk.

This hammer construction eliminates a long standing difficulty of ordinary piano hammers, particularly the repeated cutting action of the wire at the same point which soon results in a deeply grooved hammer head and adverse tonal effects. Incidentally, it is recognized that the prior art discloses an earlier proposed use of a felt disk hammer head, as shown in U.S. Patent No. 1,160,409 issued to H. W. Hicks, Nov. 16, 1915. In this patent the disk is specified as gripped by an arcuate spring in a segmental recess, with the ability to be shifted manually after wear has developed. It does not appear, however, that the feature of resilient lateral retention with self-adjusting rotation of the disk in use, as set forth in the present specification, has been either suggested or used before.

The hammer head disk 41 may optionally include weighting means such as a pellet of lead or other high density material inserted at the center. This is specifically illustrated in the larger scale drawing of FIG. 3 showing the inserted pellet 43 with an indentation 4-4 each side thereof spreading the material to retain it in the disk. Such weighting means may be graduated throughout the usual action range of eighty-eight units, or may be constant, and presents a simple and convenient method of obtaining any desired hammer head weight.

The pivotal end of the hammer shank is provided with a3 a notch 45 on its lower surface for pivotal operation on a knife-edged fulcrum t) and has a similar notch 46 on its upper surface engaged by an arcuate spring 17 adapted to maintain the hammer in spring-loaded pivotal retention on the fulcrum. The fulcrum Sit conveniently comprises a length of thin, hardened strip metal, bonded or otherwise secured to the fixed rail 51 mounted on supporting bracket 52. Rail 51 may, as shown, usefully take the form of a T-sectioncd extruded metal member with a head portion having the fulcrum means bonded thereto and a stem portion having damper rail 53 pivoted in a supporting bracket 54 mounted thereon. The damper rail is provided with an externally dovetailsshaped edge portion 53a and an axially offset end attachment comprising stub shaft 55a having a pivotal extension 560 engaging bracket 54.-

The dovetail-shaped edge portion of the damper rail is further utilized to secure damper elements 56 having internally dovetail-shaped pivotal hinge portions 57 which assemble thereon. These damper elements may advantageously be fabricated in any resilient material such as a polypropylene plastic, a material known to possess exceptional integral spring hinge properties and having the elasticity required to enable sprung assembly of the damper hinge portions over the dovetail-shaped rail edge. The damper elements further comprise integral extended arm portions having resilient string damping means 57a at one end thereof and hammer contact cushioning means 58 at the opposite end. The pivotal center as of the damper spring hinge is coaxial with the damper rail pivotal extension 56a so that the entire damper rail assembly pivots about a common center. The usual damper pedal operating means, such as a lever (not shown) may be attached to the damper rail or to an extension of the pivotal means 56a to rotate the assembly through the angular range indicated by the dotted damper rail outline 53b in FIG. 1 and 53c in FIG. 2.

The action assembly illustrated in FIG. 1 shows the parts in their initially balanced, unoperate-d position. In this relative posit-ion the flat spring attachment of the key to the rail 21 supports the weight of the front portion of the key and balances the rear key portion plus the hammer weight and hammer pivotal spring force thereon. It should be noted that the required key operating angle with the usual front key proportion is relatively small (approximately 2 degrees) and hence, that the key pivotal spring will normally be stiff enough to support it in the position shown without appreciable deflection.

If, in manufacture, key fabricating procedures result in a proportionately heavier key front portion, or with the initial setting it is found that an increased key touch resistance is desirable, the rail 21 is pivotally adjusted to the left (as viewed facing the drawing) and again secured with locknut 26 in a position to provide the required operating balance. Conversely, if the weight of the selected hammer and the hammer pivotal spring force result in relatively higher initial pressure on the disk 34 of the rear key portion, adjusting and locking the rail to the right of the position shown will provide the required opposite balancing force.

The reciprocal spring force imposed by the arcuate spring member 47 to retain the hammer on the knifeedged fulcrum, is further utilized to control hammer escapement. The established piano technique is dependent upon means to ensure unrestricted hammer impact with the string and to hold the hammer in check on rebound therefrom for instant repetition without requiring full key ascent. This requirement is simply met in the present invention by so arranging the hammer pivotal center and spring retention means that the line of the spring force acting on the notch 46 is appreciably offset from a line in the plane of the fulcrum through the pivotal notch 45. In the initial hammer position, as shown in FIG. 1, the offset spring force in addition to retaining the hammer on its pivot serves also to check appreciable rebound of the hammer from the rest pad 32. As the hammer attains the position shown in FIG. 2 in response to playing key actuation, the spring engagement notch, and thus the line of spring force thereon, progressively approaches a line in the plane of the fulcrum and pivotal notch and offers a vanishing resisting moment to the hammer approach to the string. At this point the spring force is essentially utilized only to retain the hammer shank on the fulcrum and offers negligible frictional resistance to its pivotal action thereon.

On rebound from the string the hammer, unless subjected to immediate repetition, is held and checked by its pivotal spring against opposite rebound from the key. It should be noted that the degree of rebound restraint thus imposed can be increased to any desired extent merely by increasing the distance the spring notch 46 is offset from the fulcrum notch 3-5. Any degree of restraint thus obtained, however, is supplemented by the damper contact with the hammer shank. As shown in FIG. 2. the damper has been moved from the string by the engagement of the cushioning means 58 with the hammer shank and remains thus while the hammer is held in the rebound position by the key. The spring force of the damper element thus supplements that of the hammer pivotal spring in checking rebound.

At first sight it might appear that this method of checking hammer rebound detracts from the desired hammer impact energy, but the damper spring resistance is relatively light and a very small increase in hammer weight fully compensates for the slight additional actuation force required. Also, the energy of hammer rebound from the key disk 34, being substantially less than from the string, requires proportionately less rebound restraint. It can also be observed that the hammer pivotal spring force diminishes progressively as the key pivotal spring resistance increases and consequently, that the component parts can be constructed and arranged in reciprocal spring balance either to maintain key pivotal resistance at a substantially constant rate, or to obtain other action characteristics such as described in the foregoing paragraphs.

The damper element 56, as positioned in FIG. 1, is in light contact with the string 79, with sufficient pressure for effective damping in the average small instrument. Where initially increased damper pressure is required it is obtained by pivoting the damper rail slightly more to the left, towards the position indicated by the dotted out line 53b. This adjustment increases the damper pressure on the string through increased deflection of the integral spring hinge 60.

In considering piano action means to control expression and tonal volume it can be observed that simply removing the dampers from the strings effectively releases them for maximum vibratory action, but that no comparably simple and effective means for reducing such vibratory action appears to have been developed. Shifting the action laterally for this purpose, as is customary in grand piano actions, is generally acknowledged to be objectionable in principle and apparently endures only for lack of a better method. Systems reducing the arc of hammer action or interposing a strip of felt between hammer and string are also considered unsatisfactory. An acceptable method of volume reduction should not appreciably affect either the key touch resistance or the hammer tone characteristic.

The piano action of the present invention embodies a simple and novel means for accomplishing the required tonal expression control without additional mechanism by providing for pivotal motion of the damper rail 53 in one direction to release the string damping means and motion in the opposite direction to simultaneously increase damper string pressure and reduce hammer impact force. This will be understood on reference first to FIG. 1 where pivotal motion of the damper rail to the position indicated by the dotted outline 53b will result in increased pressure of the damper element on the string 7th and will simultaneously result in increased spring resistance to the hamrncr pivotal approach to the string by contact of the cushioning means 53 with the hammer shank. A substantial reduction in sound output is obtained in this Way is ich has the further important technical advantage that it can he graduated in sheet by graduated pedal depression without interference with the designed touch and tone. Opposite, pedal actuated, pivotal motion of the damper rail to the position indicated in EC. 2 by the dotted outline 530 will move the damper eleme t to the position shown independently of hammer It will be noted, however, that the damper element remains in position for actuation by contact with. the hammer shank and checks hammer rebound from the key as described above.

One of the stated objects of this invention is to provide such action means as set forth herein capable of a simple structural modification to adapt it for use in horizontal and vertical instruments. its use in a horizontal in rument will be apparent as disclosed. its adaptation for use in a vertically disposed instrument requires only that the front end of the laying key 3? and i.s adjustable rail structure 21 be ar anged at right to the rear art of the key, all other parts and the mode of operation remaining as already disclosed.

it can be observed that the key, hammer and damper components of this disclosure are Well adapted to molded plastic iabri. ation methods, although not limited to such. The onward y angled rear key portion may alternatively be straight .nd collinear with the front key portion and e .l disk may be seoarately mounted on the head or a or adjustable capstan screw extending no 'mal to :ich straight rear key portion. The hammer rail 51 and damper rail assembly can be mounted on the key rail supporting bracket with the hammer head towards the rear and using a shorter rear key portion. Exceptional structural compactness can be realized thus. Hence, it will be understood that numerous such possible modifications of the shape and arrangement of the parts Which will uggest themselves to those knowledgeable in the art are considered to be entirely Within the scope of the invention defined in the following claims.

I claim:

1. A piano action comprising bracket means supper ing an angularly adjustable rail, a fixed rail, and a pivoted rail, said adjustable rail having a playing key in springloaded pivotal retention thereon, said fined rail having a hammer in spring-loaded pivotal retention thereon and said pivoted rail having damper means in spring-loaded pivotal retention thereon, said key being in actuating contact with said hammer and said hammer being in actuating contact with said damper means.

2. The invention as recited in claim 1, said playing key having pivotal means located between front and rear key portions, said pivotal retention comprising a length of fiat spring material disposed in the line of the key and having a portion thereof attached to said adjustable rail and a portion thereof attached to said key and being adapted to flex therebetwecn, said spring material being arranged with its fiat dimension normal to the pivotal plane of key motion.

3. The invention as recited in claim 1, said playing key having hammer actuating contact means comprising a segmental spherical recess with a resilient disk freely c. Rd

. 'lly therefrom, rnentall in said t fits projecting i, said fixed rail hammer having an knife-edged fulcrum said shank portion notched on one side thereof to pivotally said fulcrum and having an adjacent notch on an opposite side reoi enga ed by a retaining spring, tlr line of retaining spring retentive force being initially c at from a line in the plane of said fulcrum and r :gressively approaching thereto during hammer pivotal action.

e. The invention as recited in claim 1 said a hammer comprising a head portion having a segments. spherical .s and a resilient disk freely inserted therein and liy projecting therefrom, said disk being adapted ..e incrementally therein in response to tangential contact of i s projecting portion with a piano string.

ntion as recited in claim 1 wh rein the said inve having i each end thereof, one of said pads being en piano string vibration and the other g adapted to cushion damper actuating u hammer.

. invention as recited in claim 3. wherein the said ther comprises a key pivotal soring rec i ing with playing key d ction and a hammer tal suring force decreasing therewith.

he invention as recited in claim 2 including means for piano tone expression control comprising axial rota tion of said pivoted rail to remove said damper means from contact with a piano string and opposite rotation thereof to simultaneously increase pressure of said damper means on a piano string and reduce hammer impact thereon.

9. A piano action comprising supporting bracket means having an angularly adjustable key rail pivoted thereto, a playing key flexuraliy pivoted on said key rail, a hammer rail having a hammer in fierrurally pivoted retention thereon, and a pivotally bracketed damper rail having damper elements ilexurally pivoted thereon, each of said tlcxurally pivoted members being in consecutive flexurally-loaded actuating contact with each other.

iii. The invention as recited in claim 9, said action being adapted for control means comprising pivotal rotation of said damper rail in one direction to simultaneously increase the pressure of said damper on a piano string and reduce hammer impact thereon, and pivotal rotation of said damper rail in an opposite direction to simultaneously reduce said pressure on said string and increase hammer impact thereon.

11. The invention as recited in claim 9, said hammer comprising a head portion having a segmental spherical recess and having a resilient disk freely inserted therein and projecting segmentally therefrom, said disk being adapted to rotate incrementally in said recess in response to tangential frictional contact with a piano string and having Weighting means secured thereto.

No references cited.

LEO SMILOW, Primary Examii'zer. 

1. A PIANO ACTION COMPRISING BRACKET MEANS SUPPORTING AN ANGULARLY ADJUSTABLE RAIL, A FIXED RAIL, AND A PIVOTED RAIL, SAID ADJUSTABLE RAIL HAVING A PLAYING KEY IN SPRINGLOADED PIVOTAL RETENTION THEREON, SAID FIXED RAIL HAVING A HAMMER IN SPRING-LOADED PIVOTAL RETENTION THEREON AND SAID PIVOTED RAIL HAVING DAMPER MEANS IN SPRING-LOADED PIVOTAL RETENTION THEREON, SAID KEY BEING IN ACTUATING CONTACT WITH SAID HAMMER AND SAID HAMMER BEING IN ACTUATING CONTAC WITH SAID DAMPER MEANS. 